locus

Also known as Cytogenetic location, loci, chromosomal locus, chromosomal locus of a gene, locus of a gene, genetic locus, genetic loci, DNA loci

location of a gene at a chromosome

AI overview

A locus is the specific location where a gene sits on a chromosome, like an address for that gene. It matters because knowing where genes are located helps scientists understand heredity, identify genetic diseases, and track how traits are passed from parents to children.

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Commons category: Locus (genetics)

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Article

Parts of a typical chromosome:(1) Chromatid(2) Centromere(3) Short (p) arm(4) Long (q) arm In genetics, a locus (pl.: loci) is a specific, fixed position on a chromosome where a particular gene or genetic marker is located. Each chromosome carries many genes, with each gene occupying a different position or locus; in humans, the total number of protein-coding genes in a complete haploid set of 23 chromosomes is estimated at 19,000–20,000.

Genes may possess multiple variants known as alleles, and an allele may also be said to reside at a particular locus. Diploid and polyploid cells whose chromosomes have the same allele at a given locus are called homozygous with respect to that locus, while those that have different alleles at a given locus are called heterozygous. The ordered list of loci known for a particular genome is called a gene map. Gene mapping is the process of determining the specific locus or loci responsible for producing a particular phenotype or biological trait. Association mapping, also known as "linkage disequilibrium mapping", is a method of mapping quantitative trait loci (QTLs) that takes advantage of historic linkage disequilibrium to link phenotypes (observable characteristics) to genotypes (the genetic constitution of organisms), uncovering genetic associations.